Place the peanuts in a food processor and pulse into a rough crumble. Remove the peanuts and place in a bowl.
Roughly chop the celery, then place in the food processor. Pulse the celery until the pieces resemble coarse mince.
Heat the veg oil in a pan or wok. When hot, add the celery and peanuts. Cook for 15-20 minutes over a medium heat, stirring frequently to remove as much water as possible. The celery will give off water as it cooks down. When appearing more dry, add the garlic and soy sauce, and cook for a further 5 minutes. Take off the heat and leave to cool. Transfer to a bowl.
Have a small bowl of water handy to wet the wonton wrappers, helping them stick. There are many traditional wonton folding shapes. I learned this method from my student’s mother in Shanghai, a woman I often cooked with. To fill the wontons, wet the bottom side of the wonton square. Add a generous teaspoon of filling in the middle of the square. Pull the wet side of the wrapper toward the top of the square, but not all the way to the top, aligning and attaching 1/2 inch from the top. Now you have a flat rectangle shape with the filling at the bottom and the seam at the top. At the top of the filling section, start folding the filling up toward the top, just partway. Leave the top edge of the wrapper still visible. Bring the open left and right sides together, wetting one side while you attach them, sealing well.
To cook as wonton soup, poach the wontons in a light broth at a rolling boil until the wrappers start to look translucent. Stir gently so the wontons don’t stick to the pot.
Serve in the broth.